Magnet wire insulation comprising a high-temperature sulfone polymer blend

ABSTRACT

A magnet wire containing a melt processable, thermoplastic resin blend insulative coating developed for use in high temperature electrical insulation systems. The invention relates to a high temperature electrical insulation containing a sulfone polymer blend for particular use with magnet wire. The sulfone polymer blend contains two poly(aryl ether sulfones), such as polyphenylsulfone and polysulfone.

This application claims the benefit of U.S. Provisional Application No.60/389,484, filed on Jun. 19, 2002.

FIELD OF THE INVENTION

This invention relates to a magnet wire comprising a melt processable,thermoplastic resin blend insulative coating developed especially foruse in high temperature electrical insulation systems. Moreparticularly, this invention relates to a high temperature electricalinsulation system containing sulfone polymers for use with magnet wireand wherein the sulfone polymers comprise a blend of two poly(aryl ethersulfones). The blend exhibits improved electrical insulation and longterm thermal and environmental aging stability relative to polysulfone.

BACKGROUND OF THE INVENTION

Polymeric materials are used in magnet wire insulation coatings.Although thermoset materials are commonly used, magnet wire insulationcoatings can include thermoplastics. These polymeric materials areapplied as extruded coatings, wrapped films, powder coatings, andsolvent-based enamels. Paper is also commonly used as wire wrapinsulation.

Examples of thermoplastic polymers used in magnet wire insulationsystems include poly(aryl ether sulfones), such as polyphenylsulfone. Amagnet wire comprising a polyphenylsulfone resin insulation iscommercially available under the tradename Reymag® produced by HanoverManufacturing Corporation. Polyphenylsulfone is a tough linear polymerthat possesses a number of attractive features such as excellent hightemperature resistance, good electrical properties, high ductility, goodtoughness, and very good hydrolytic stability. Polyphenylsulfone isavailable from Solvay Advanced Polymers, LLC, under the trademark ofRadel® R. It corresponds to the following repeat unit formula:

and has a Tg of about 220° C. It is produced by the polycondensation ofbiphenol with 4,4′-dichlorodiphenyl sulfone as described in CanadianPatent No. 847,963. Polyphenylsulfone is an expensive resin due to thehigh cost of biphenol.

High temperature insulation systems for magnet wire are required in manyapplications including transformers, motors, generators, solenoids, andrelays. Requirements for such products include high efficiency or lowdissipation at use temperatures; high continuous use temperatures;resistance to insulating fluids such as a mineral oil, a silicone oil, avegetable oil, a synthetic oil, and mixtures thereof; and ability towithstand overload conditions. Not only is the magnet wire coatingrequired to provide dielectric insulation, but it also must provideprotection against abrasion, mechanical stress, and corrosion. Thus,magnet wire insulation systems have many more stringent requirementsover mere dielectric insulation. There is, therefore, a continual needin the art to economically improve the performance of insulation systemsfor magnet wire.

SUMMARY OF THE INVENTION

There exists a need in the magnet wire art for high performanceinsulation coatings that exhibit robust electrical insulation, long termthermal aging stability, and environmental resistance. There exists aneed in the magnet wire art to economically produce high performancemagnet wire insulation coatings, by reducing the amount of expensiveresins used in the insulation coating. Further, there exists a need inthe magnet wire art to produce high performance insulation coatingscontaining minimal amounts of consumable performance and stabilityadditives. In addition, there exists a need in the magnet wire art to beable to economically and reliably insulate the wire by extrusioncoating, solvent coating, film wrapping or powder coating.

In addition, there exists a need in the electrical device art for anelectrical device comprising insulated magnet wire that can withstandlong term exposure to high temperature. There further exists a need inthe electrical device art for an electrical device comprising insulatedmagnet wire that has superior chemical resistance during long termexposure to oils.

These and other needs are met by certain embodiments of the presentinvention, that provide an insulated magnet wire comprising a metallicmagnet wire and a polymer composition insulation coating, wherein theinsulation coating comprises a blend of polyphenylsulfone (PPSF) andpolysulfone (PSF), wherein the PPSF comprises the following structuralrepeat unit:

and the PSF comprises the following structural repeat unit:

The earlier-stated needs are further met by an electrical devicecomprising an insulated magnet wire comprising a metallic wire and apolymer composition insulating coating, wherein the insulation coatingcomprises a blend of polyphenylsulfone (PPSF) and polysulfone (PSF),wherein the PPSF comprises the following structural repeat unit:

and the PSF comprises the following structural repeat unit:

The earlier-stated needs are further met by certain embodiments of thepresent invention that provide an insulated magnet wire comprising ametallic magnet wire and a polymer composition insulation coatingcomprising from about 20 wt. % to about 80 wt. % PPSF and about 20 wt. %to about 80 wt. % PSF based on the total polymer weight.

Additional advantages and aspects of the present invention will becomereadily apparent to those skilled in the art from the following detaileddescription, wherein embodiments of the present invention are shown anddescribed, simply by way of illustration of the best mode contemplatedfor practicing the present invention. As will be described, the presentinvention is capable of other and different embodiments, and its severaldetails are susceptible to modification in various obvious respects, allwithout departing from the spirit of the present invention. Accordingly,the description is to be regarded as illustrative in nature, and not aslimitative.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an insulated magnet wire according to an embodimentof the present invention.

FIG. 2 illustrates an electrical device according to an embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides magnet wire with a robust electricalinsulation coating. The present invention provides a high performancepoly(aryl ether sulfone) blend which exhibits improved electricalinsulation and long term thermal aging stability. The present inventionallows for the economical production of a magnet wire comprising a highperformance poly(aryl ether sulfone) blend coating with optional amountsof performance and stability additives. The present invention allows forthe production of an insulated magnet wire with a reduced amount of anexpensive resin, such as PPSF, which retains the high performanceproperties of PPSF. Coupled with all the above benefits, the presentinvention allows for the economical fabrication of metallic magnet wirewith a thermoplastic blend containing poly(aryl ether sulfones). Thesebenefits are provided by an insulated magnet wire comprising a metallicmagnet wire and a polymer composition insulation coating, said polymercomposition insulation coating comprising a blend of polyphenylsulfone(PPSF) and polysulfone (PSF). The PPSF comprises the followingstructural repeat unit:

-   -   and the PSF comprises the following structural repeat unit:

PPSF is available from commercial sources, including Solvay AdvancedPolymers, LLC, under the trademark of Radel® R. Suitable PPSF forcertain embodiments of the present invention has a Tg of about 220° C.PPSF is produced by the polycondensation of biphenol with4,4-dichlorodiphenyl sulfone as described in Canadian Patent No.847,963, the entire disclosure of which is incorporated herein. Incertain embodiments, the PPSF can be a copolymer wherein up to less than50 mole % of the biphenol residue structural units are substituted withone or more aromatic dihydroxy compound residues other than those frombiphenol. The aromatic dihydroxy compound residues other than those frombiphenol are selected from the group consisting of4,4′-isopropylidenediphenol (bisphenol A), 4,4′-dihydroxydiphenylether(bisphenol O), 4,4′-dihydroxydiphenylsulfone (bisphenol S),4,4′-dihydroxybenzophenone, 1,4-bis(4-hydroxyphenyl) benzene, andhydroquinone.

PSF is available from commercial sources, including from Solvay AdvancedPolymers, LLC, under the trademark of UDEL®. Suitable PSF for certainembodiments of the present invention and has a Tg of about 185° C. PSFis made via the nucleophilic polycondensation of bisphenol-A di-sodiumsalt with 4,4′-dichlorodiphenyl sulfone, as described in U.S. Pat. No.4,108,837, the entire disclosure of which is incorporated herein. Incertain embodiments, the PSF can be a copolymer wherein up to less than50 mole % of the bisphenol A residue structural units are substitutedwith one or more aromatic dihydroxy compound residues other than thosefrom bisphenol A. The aromatic dihydroxy compound residues other thanthose from bisphenol A are selected from the group consisting of4,4′-dihydroxydiphenylether (bisphenol O), 4,4′-dihydroxydiphenylsulfone(bisphenol S), 4,4′-dihydroxybenzophenone, 1,4-bis(4-hydroxyphenyl)benzene, 4,4′-dihydroxydiphenyl (biphenol) and hydroquinone.

Properties of the PPSF/PSF blend provide benefits in the end-useapplications of magnet wire. For example, PPSF/PSF blend coated magnetwire can be wound faster with fewer insulation tears than paper wrappedwire. The required insulation thickness is generally less than thatrequired for paper wrapped wire which can yield smaller windings.Moreover, because the PPSF/PSF blend has a low equilibrium moisturecontent, magnet wire coils can be dried quickly and do not contribute tohydrolysis of insulating oils. In addition, the PPSF/PSF blend canperform under higher temperatures and more rigorous conditions in oilenvironments thereby reducing susceptibility to damage under overloadconditions. The end result is increased reliability and longer servicetime. Furthermore, PPSF/PSF blend coated magnet wire uses a reducedamount of expensive PPSF resin, while retaining the high performanceproperties of PPSF required for magnet wire applications.

In FIG. 1, an insulated magnet wire 10 according to an embodiment of thepresent invention is depicted. Insulated magnet wire 10 comprises magnetwire 12 which can be comprised of a copper, aluminum and the like.Magnet wire 12 is coated with insulation coating 14 that is applied tomagnet wire 12 to provide a continuous coating.

Other embodiments of the present invention include an insulated magnetwire comprising a metallic magnet wire and a polymer compositioninsulation coating that comprises from about 20 wt. % to about 80 wt. %PPSF and about 20 wt. % to about 80 wt. % PSF based on the total polymerweight. In certain embodiments of the present invention the insulatedmagnet wire comprises a metallic magnet wire and a polymer compositioninsulation coating that comprises greater than 50 wt. % PPSF based onthe total polymer weight. In other certain embodiments of the presentinvention the insulated magnet wire comprises a metallic magnet wire anda polymer composition insulation coating that comprises from about 30wt. % to about 70 wt. % PPSF and about 30 wt. % to about 70 wt. % PSFbased on the total polymer weight. In other certain embodiments of thepresent invention the insulated magnet wire comprises a metallic magnetwire and a polymer composition insulation coating that comprises fromabout 40 wt. % to about 60 wt. % PPSF and about 40 wt. % to about 60 wt.% PSF based on the total polymer weight. Other certain embodiments ofthe present invention include a magnet wire composition comprising ametallic magnet wire and a polymer composition insulation coatingcomprising about 70 wt. % PPSF and about 30 wt. % PSF based on the totalpolymer weight. Other embodiments of the present invention include amagnet wire comprising a metallic magnet wire and a polymer compositioninsulation coating comprising about 55 wt. % PPSF and about 45 wt. % PSFbased on the total polymer weight.

The PPSF/PSF blend of the present invention, may optionally includereinforcing filler, fiber, pigments, additives, and the like.Representative fibers which may serve as reinforcing media include glassfibers, asbestos, synthetic polymeric fibers, aluminum silicate fibers,wollastonite, rock wool fibers, etc. Representative filler and othermaterials include glass, calcium silicate, silica, clays, talc, mica;pigments such as carbon black, titanium dioxide, zinc oxide, iron oxide,cadmium red and iron blue; polymers such as polyethersulfone; and otheradditives such as, alumina trihydrate, sodium aluminum carbonate, andbarium ferrite. Additional additives commonly employed in the magnetwire art such as thermal stabilizers, ultraviolet light stabilizers,plasticizers, and the like, may be included. Titanium dioxide and zincoxide pigments are well suited for use in certain embodiments of thepresent invention.

Other certain embodiments of the present invention include a method forproviding an insulated magnet wire with a polymer composition insulationcoating, the method comprising the step of coating a polymer compositioninsulation on a metallic magnet wire. The polymer composition insulationcoating comprises a blend of polyphenylsulfone (PPSF) and polysulfone(PSF), wherein the PPSF comprises the following structural repeat unit:

-   -   and the PSF comprises the following structural repeat unit:

Other embodiments of the present invention include a method of providingan insulated magnet wire with a polymer composition insulation coating,wherein the insulation coating comprises from about 20 wt. % to about 80wt. % PPSF and about 20 wt. % to about 80 wt. % PSF based on the totalpolymer weight. In certain embodiments of the present invention theinsulated magnet wire comprises a metallic magnet wire and a polymercomposition insulation coating that comprises greater than 50 wt. % PPSFbased on the total polymer weight. In other certain embodiments of thepresent invention the insulated magnet wire comprises a metallic magnetwire and a polymer composition insulation coating that comprises fromabout 30 wt. % to about 70 wt. % PPSF and about 30 wt. % to about 70 wt.% PSF based on the total polymer weight. In other certain embodiments ofthe present invention the insulated magnet wire comprises a metallicmagnet wire and a polymer composition insulation coating that comprisesfrom about 40 wt. % to about 60 wt. % PPSF and about 40 wt. % to about60 wt. % PSF based on the total polymer weight. Other certainembodiments of the present invention include a method of providing aninsulated magnet wire with a polymer composition insulation coating,wherein the insulation coating comprises about 70 wt. % PPSF and about30 wt. % PSF based on the total polymer weight. Other embodiments of thepresent invention include a method of providing an insulated magnet wirewith a polymer composition insulation coating, wherein the insulationcoating comprises about 55 wt. % PPSF and about 45 wt. % PSF based onthe total polymer weight.

Additional advantages realized through the use of present invention'sinsulated magnet wire is the ability to fabricate insulated magnet wireusing multiple techniques. Insulation can be applied by wrapping plasticextruded or solvent cast film. It can also be applied by solvent coatinglike other common enamels or by known powder coating techniques. In thecase of solvent coating, an oven step is used only for the purpose ofdriving off solvent rather than curing and driving off solvent.

The most efficient and cost effective method is to melt extrude thecoating directly on the magnet wire. In melt extrusion fabrication,solvent recovery systems are not required and curing steps are optional.Extruders required to provide the necessary throughput for wire coatingapplications are quite small and economical to install. The excellentthermal stability of the PPSF/PSF insulation coating also allows meltextrusion processing of magnet wire at fabrication temperatures up to400° C. Magnet wire can be prepared either by conforming, drawing, orrolling. The PPSF/PSF insulation coating of the present invention may beused with round and shaped aluminum and copper wire of varying size.

Other embodiments of the present invention include forming the magnetwire and then coating the wire by a metal conforming line and meltextrusion coating line in tandem. A variety of round and rectangularwire sizes are produced via this technique. The metallic magnet wire isparticularly suitable for use in oil-filled transformers.

Other certain embodiments of the present invention include a method forproviding an insulated magnet wire comprising the PPSF/PSF polymercomposition insulation coating. The method includes the step of meltextruding. The melt extrusion process comprises providing a supply ofmetal feed stock and continuously feeding the feed stock into a rotaryextrusion press and continuously forming the magnet wire. The magnetwire can be formed in tandem with the extrusion operation or it can beformed in a separate step and heated prior to the polymer compositioncoating. The metal wire can be formed as described above with a rotaryextrusion press, or it may be drawn. It may also be formed by rolling orflattening round wire into a rectangular shape. The extruded magnet wireis moved through extrusion die at a set speed. In certain embodiments ofthe present invention, sulfone polymer-based insulation coating of thepresent invention is extruded using a tubing or semi-tubing techniquewhich involves a crosshead assembly and a tip and die configuration thatcontains flow channels designed to maximize the uniformity of thecoating on shaped magnet wire. The tube is extruded around and spacedfrom the extruded magnet wire, and the tube is extruded such that thethickness of the polymer material is reduced or drawn down before itcontacts the extruded magnet wire. A vacuum is provided between theextruded magnet wire and the polymeric material being extruded therebycausing atmospheric pressure to progressively press the extrudedpolymeric material into contact with the extruded magnet wire.Application of the polymer through means of pressure extrusion techniquemay also be suitable. In pressure extrusion, metal wire is brought intocontact with molten polymer within the crosshead die to form the coatingand no tube is extruded. The magnet wire is extruded in a heatedcondition, but the temperature is controlled to a suitable range forapplication of the polymeric material to the wire. The temperature isselected to control the cooling rate of the polymer on the wire which inturn can minimize stress in the coating and maximize adhesion of thecoating to the magnet wire. The particular metal of the magnet wire isnot critical and may include any commonly used electrically conductivematerial including, for example, aluminum, aluminum-based alloys,copper, and copper-based alloys.

Other embodiments of the present invention include using the insulatedmagnet wire of the present invention in high temperature electricalinsulation systems. Suitable high temperature electrical insulationsystems include electrical devices, including voltage transformers,motors, generators, alternators, solenoids, relays, and the like. InFIG. 2, transformer 20, according to an embodiment of the presentinvention is depicted. Transformer 20 comprises two coils 21 a, 21 b ofinsulated magnet wire, which are wrapped around core 30. Transformer 20can be a step-up transformer, wherein coil 21 a will be a primary coil(i.e. has an electric current passed through it) and coil 21 b will be asecondary coil (has an electric current induced within it).Alternatively, transformer 20 can be a step-down transformer, whereincoil 21 a will be a secondary coil (has an electric current inducedwithin it) and coil 21 b will be a primary coil (i.e. has an electriccurrent passed through it). In either embodiment, core 30 is a magnetcomprised of iron, or the like.

Properties of the PPSF/PSF blend, Example 1, are depicted in Table 1,and are compared with the PPSF resin, Control 1. The PPSF/PSF blendabsorbs slightly less moisture than PPSF and exhibits greater meltstability than PPSF. Melt stability is characterized by measuring theratio of melt viscosity measured at 50 reciprocal seconds after exposureto 410° C. for 40 minutes to the melt viscosity measured after 10minutes. The PPSF/PSF blend exhibits a viscosity ratio of 1.3 versus 1.5which is typical of PPSF resins. Example 1 is a 70 wt. %/30 wt. % basedon the total polymer weight RADEL® R PPSF/UDEL® PSF blend. Asdemonstrated, the PPSF/PSF blend has comparable superior flameresistance, mechanical strength, and minimum moisture absorption, as thePPSF resin, Control 1. These properties demonstrate the compatibility ofthe PPSF/PSF blend with magnet wire applications. Further, the PPSF/PSFblend exhibits superior properties over the PSF resin, ComparativeExample 1. The supertough behavior of the PPSF/PSF blend is evidenced bythe high notched Izod impact strength. Further the PPSF/PSF blendexhibits superior thermal properties over the PSF resin, as evidenced bythe heat deflection temperature results in Table 1. It is noted that theglass transition temperature for the PPSF/PSF blend is 185/220 due tothe immiscible blend of the two polymers (i.e. one glass transitiontemperature will occur for each polymer). TABLE 1 Selected Properties ofPolyphenylsulfone and a Polyphenylsulfone Blend Example 1 Compara- 70wt. % tive PPSF/ Example 1 Control 1 30 wt. % Physical Method Units PSFPPSF PSF Blend Moisture Absorption ASTM — After 24 hrs D-570 % 0.3 0.370.30 At Equilibrium D-570 % 0.6 1.1 0.95 Specific Gravity D-792 1.241.29 1.28 Mechanical Tensile Strength D-638 MPa 70 70 70 Elongation atBreak D-638 % 50-100 90 60 Flexural Strength D-790 MPa 105 105 105Notched D-256 J/m 69 694 265 Izod Impact Un-notched Izod D-256 J/m 0Breaks 0 Breaks 0 Breaks Thermal Glass Transition ° C. 185 220 185/220Temp. Heat D-648 ° C. 174 207 200 Deflection Temp. Electrical DielectricConstant after 48 hours of conditioning at 23° C. and 50% RH @ 1 MHzD-150 — 3.1 3.45 3.40 Flammability Limiting Oxygen D-2863 % 26 38 36Index

Relevant performance characteristics of aluminum wire coated with thePPSF/PSF insulation blend were evaluated and the results are given inTable 2. It can be seen in Table 2 that wire coated with the PPSF/PSFblend exhibits good flexibility, adhesion, and elongation, comparable toaluminum wire coated with the more expensive PPSF resin. The PPSF/PSFmagnet wire insulation is also resistant to heat shock, and can maintaindielectric strength at temperatures up to 200° C. At temperatures of200° C., the dissipation remains at about 0.007 which is far lower thanmany polyvinylformal based resins and paper. Thus, the magnet wirescoated with the present invention's insulative coating are suitable foruse with high temperature systems. TABLE 2 NEMA MW 1000 Quality Tests ofMagnet Wire Using Test Methods NEMA MW 1000/ASTM D-1676. Allmeasurements made by Eltek International Laboratories on rectangularaluminum magnet wire. Test Control 1 Example 1 Aluminum Bare Wire Width0.3253 in 0.3251 in Thickness 0.1137 in 0.1138 in Overall DimensionsWidth 0.3367 in 0.3349 in Thickness 0.1208 in 0.1201 in Increase inDimension Width 0.1140 in 0.0098 in Thickness 0.0071 in 0.0063 inAverage Film Build Width 0.0057 in 0.0049 in Thickness 0.0036 in 0.0032in Elongation to Break 20% (Rectangular Wire) 33% 35% (Round Wire)(Rectangular Wire) Flatwise Bend No cracks visible in the film No cracksvisible in the film coating coating Egdewise Bend No cracks visible inthe film No cracks visible in the film coating coating Windability Nocracks visible in the film No cracks visible in the film coating coatingHeat Shock No cracks visible in the film No cracks visible in the filmcoating after conditioning at coating after conditioning at 260° C. 175°C. Thermoplastic Flow 265° C. 245° C. Breakdown Voltage after 48 hoursof conditioning at 23° C. and 50% RH 23° C. 10.88 kV 9.30 kV 150° C. 8.96 kV 9.32 kV 180° C.  8.79 kV 8.48 kV 200° C.  8.90 kV 7.07 kVDissipation after 48 hours of conditioning at 23° C. and 50% Rh 23° C.0.0022 0.0016 150° C. 0.0007 0.0008 180° C. 0.0021 0.0042 200° C. 0.00420.0069

The insulation coating of the present invention also retains propertiesafter over 5 months of aging in hot transformer oil, and the results aregiven in Table 3. The wires were coated with resin by drawing themthrough a melt-flow apparatus. By passing the wire through the die, andkeeping the apparatus primed with resin pellets, a coating was passedthrough the die and on to the bare wire. For each coated wire, a lengthwas wrapped around a rod ¼″ in diameter, and 1/16″ in diameter toresemble a spring. Two straight lengths of wire at approximately 2-3″were also cut. The wires were then placed into a glass-lined Parrreactor with sufficient transformer oil to submerge the wires. Thereactor was placed in an oven and the temperature was set to 150° C. Thewires were subjected to the heated oil in the reactor at a temperatureof about 150° C.±1° C. The reactor was periodically removed from theoven, cooled to room temperature, and the wire samples were removed fromthe reactor for evaluation. Following each evaluation the wires werere-submerged in the oil contained in the glass-lined Parr reactor.Evaluations were taken at different intervals, and the results aresummarized in Table 3.

The PPSF resin (RADEL® R) does not exhibit any failure in this hot oilenvironment. Moreover, it is evident that the resin blend (PPSF/PSF) ofthe present invention did not exhibit stress-cracking behavior evenafter a period of 5 months. The results are unexpected in view of theproximity of the hot oil environment temperature to the glass transitiontemperatures (Tg) of the PSF contained in the blend and the increasedenvironmental sensitivity that might be expected for the PSF at thistemperature. The PSF resin has a lower glass transition temperature(Tg=185° C.), compared to the PPSF resin (Tg=220° C.). Further, the testsample containing the PSF resin (UDEL®) exhibited stress-crackingbehavior after exposure to the silicone oil at 150° C. after only oneweek. However, the resin blend (70 wt. % PPSF/30 wt. % PSF) of thepresent invention did not exhibit stress-cracking behavior during thehot oil aging experiment. Thus, the PPSF/PSF resin blend used in thepresent invention offers high performance properties that arecharacteristic of the PPSF resin. TABLE 3 Hot Transformer Oil ExperimentRESIN DAY 1 DAY 20 DAY 48 DAY 56 DAY 97 DAY 145 DAY 156 PPSF InsulatedClean and Same as Same as Same as Same as Same as wire free of Day 20 -Day 48 - Day 56 - Day 97 - Day 145 - submerged cracks and no no no no noin oil crazing - significant significant significant significantsignificant no change change change change change significant change 70wt. % Insulated Clean and Same as Same as Same as Same as Same as PPSF/wire free of Day 20 - Day 48 - Day 56 - Day 97 - Day 145 - 30 wt. %submerged cracks and no no no no no PSF in oil crazing - significantsignificant significant significant significant Blend no change changechange change change significant change PSF Insulated Straight Same asSame as Same as Same as Same as wire wires Day 20 - Day 48 - Day 56 -Day 97 - Day 145- submerged crazed and no no no no no in oil springssignificant significant significant significant significant have changechange change change change cracks

The present invention enjoys industrial applicability in the productionof insulated magnet wire for use with high temperature electricalinsulation systems. The present invention is particularly applicable inthe production of insulated magnet wire having a polymer insulationcoating for use with high temperature electrical insulation systems.Further, the present invention is particularly applicable in theproduction of magnetic wire having a poly(aryl ether sulfone) blendinsulative coating, exhibiting robust electrical insulation and longterm thermal aging stability along with improved economics over thecurrent art.

Only the preferred embodiment of the present invention and a fewexamples of its versatility are shown and described in the presentdisclosure. They should not be construed to limit the scope of theclaims. It is understood by one of ordinary skill in this art that thepresent invention is capable of use in various other combinations andenvironments and is susceptible of changes or modifications within thescope of the inventive concept as expressed herein.

1. An insulated magnet wire comprising a metallic magnet wire and apolymer composition insulation coating, said polymer compositioninsulation coating comprising a blend of a polyphenylsulfone (PPSF) anda polysulfone (PSF), wherein the PPSF comprises the following structuralrepeat unit:

and the PSF comprises the following structural repeat unit:


2. The insulated magnet wire according to claim 1, wherein theinsulation coating comprises from about 20 wt. % to about 80 wt. % PPSFand about 20 wt. % to about 80 wt. % PSF based on the total polymerweight.
 3. The insulated magnet wire according to claim 2, wherein theinsulation coating comprises greater than 50 wt. % PPSF based on thetotal polymer weight.
 4. The insulated magnet wire according to claim 1,wherein the insulation coating comprises about 70 wt. % PPSF and about30 wt. % PSF based on the total polymer weight.
 5. The insulated magnetwire according to claim 1, wherein the insulation coating comprisesabout 55 wt. % PPSF and about 45 wt. % PSF based on the total polymerweight.
 6. The insulated magnet wire according to claim 1, wherein theinsulation coating further comprises at least one reinforcing filler,fiber, pigment and/or additive.
 7. The insulated magnet wire accordingto claim 6, wherein the fiber is selected from the group consisting ofglass fiber, asbestos, synthetic polymeric fiber, aluminum silicatefiber, wollastonite and rock wool fiber.
 8. The insulated magnet wireaccording to claim 6, wherein the reinforcing filler is selected fromthe group consisting of glass, calcium silicate, silica, clays, talc andmica.
 9. The insulated magnet wire according to claim 6, wherein thepigment is selected from the group consisting of carbon black, titaniumdioxide, zinc oxide, iron oxide, cadmium red and iron blue.
 10. Theinsulated magnet wire according to claim 9, wherein the pigment istitanium dioxide or zinc oxide.
 11. The insulated magnet wire accordingto claim 1, wherein the PPSF can be a copolymer wherein up to less than50 mole % of the biphenol residue structural units are substituted withone or more aromatic dihydroxy compound residues other than those frombiphenol, and wherein the aromatic dihydroxy compound residues otherthan those from biphenol are selected from the group consisting of4,4′-isopropylidenediphenol, 4,4′-dihydroxydiphenylether,4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxybenzophenone,1,4-bis(4-hydroxyphenyl) benzene, and hydroquinone.
 12. The insulatedmagnet wire according to claim 1, wherein the PSF can be a copolymerwherein up to less than 50 mole % of the bisphenol A residue structuralunits are substituted with one or more aromatic dihydroxy compoundresidues other than those from bisphenol A, and wherein the aromaticdihydroxy compound residues other than those from bisphenol A areselected from the group consisting of 4,4′-dihydroxydiphenylether,4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxybenzophenone,1,4-bis(4-hydroxyphenyl) benzene, 4,4′-dihydroxydiphenyl andhydroquinone.
 13. A method for providing an insulated magnet wire with apolymer composition insulation coating, said method comprising coating apolymer composition insulation on a bare metallic magnet wire, saidpolymer composition insulation coating comprising a blend of apolyphenylsulfone (PPSF) and a polysulfone (PSF), wherein the PPSFcomprises the following structural repeat unit:

and the PSF comprises the following structural repeat unit:


14. The method according to claim 13, wherein the insulation coatingcomprises from about 20 wt. % to about 80 wt. % PPSF and about 20 wt. %to about 80 wt. % PSF based on the total polymer weight.
 15. The methodaccording to claim 14, wherein the insulation coating comprises greaterthan 50 wt. % PPSF based on the total polymer weight.
 16. The methodaccording to claim 13, wherein the insulation coating comprises about 70wt. % PPSF and about 30 wt. % PSF based on the total polymer weight. 17.The method according to claim 13, wherein the insulation coatingcomprises about 55 wt. % PPSF and about 45 wt. % PSF based on the totalpolymer weight.
 18. The method according to claim 13, wherein thecoating step is selected from the group consisting of melt extruding,solvent coating, powder coating and film wrapping.
 19. The methodaccording to claim 18, wherein the coating step is melt extruding. 20.The method according to claim 13, wherein the metallic magnet wire ispreheated prior to extruding the insulation coating on the metallicmagnet wire.
 21. The method according to claim 13, wherein theinsulation coating is melt filtered prior to being extruded on themetallic magnet wire.
 22. The method according to claim 13, wherein saidmelt extruding step is free of solvent.
 23. The method according toclaim 13, further comprising an optional baking step to cure saidcoating.
 24. The method according to claim 23, further comprisingcooling the cured coating on said metallic magnet wire.
 25. The methodaccording to claim 13, wherein the PPSF can be a copolymer wherein up toless than 50 mole % of the biphenol residue structural units aresubstituted with one or more aromatic dihydroxy compound residues otherthan those from biphenol, and wherein the aromatic dihydroxy compoundresidues other than those from biphenol are selected from the groupconsisting of 4,4′-isopropylidenediphenol, 4,4′-dihydroxydiphenylether,4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxybenzophenone,1,4-bis(4-hydroxyphenyl) benzene, and hydroquinone.
 26. The methodaccording to claim 13, wherein the PSF can be a copolymer wherein up toless than 50 mole % of the bisphenol A residue structural units aresubstituted with one or more aromatic dihydroxy compound residues otherthan those from bisphenol A, and wherein the aromatic dihydroxy compoundresidues other than those from bisphenol A are selected from the groupconsisting of 4,4′-dihydroxydiphenylether,4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxybenzophenone,1,4-bis(4-hydroxyphenyl) benzene, 4,4′-dihydroxydiphenyl andhydroquinone.
 27. A high temperature electrical insulation systemcomprising said insulated magnet wire according to claim
 1. 28. The hightemperature electrical insulation system according to claim 27, whereinthe high temperature electrical insulation system is selected from thegroup consisting of voltage transformers, motors, generators,alternators, solenoids, and relays.
 29. A high temperature electricalinsulation system comprising an insulated magnet wire obtained by theprocess according to claim
 13. 30. (canceled)
 31. The high temperatureelectrical insulation system according to claim 27, wherein the metallicmagnet wire is in contact with an insulating fluid selected from thegroup consisting of a mineral oil, a silicone oil, a vegetable oil, asynthetic oil, and mixtures thereof.
 32. An electrical device comprisingsaid insulated magnet wire according to claim
 1. 33. The electricaldevice according to claim 32, wherein said electrical device is selectedfrom the group consisting of voltage transformers, motors, generators,alternators, solenoids, and relays.
 34. The high temperature electricalinsulation system according to claim 29, wherein the high temperatureelectrical insulation system is selected from the group consisting ofvoltage transformers, motors, generators, alternators, solenoids, andrelays.
 35. The high temperature electrical insulation system accordingto claim 29, wherein the metallic magnet wire is in contact with aninsulating fluid selected from the group consisting of a mineral oil, asilicone oil, a vegetable oil, a synthetic oil, and mixtures thereof.